Field of the Invention
The present invention relates to a light emitting diode and a package of a light emitting diode.
Description of the Related Art
A light emitting diode (LED) is a light emitting device constituting a light source by using compound semiconductor materials such as GaAs, AlGaAs, GaN, InGaN, and AlGaInP. The LED has the advantage of emitting various colors on materials of the semiconductor.
Generally, the characteristics of the LED are determined according to high-luminance light-emitting, luminance, color range of the emitted light, and the like. The characteristics of the LED device are primary determined by the compound semiconductor materials used in the LED device. Also, the characteristics are secondly determined by package construction for mounting a chip. Especially, in order to obtain distribution of a luminance angle according to high luminance and user requirements, the primary element of the materials is limited. So, recently, many people are interested in the package construction.
The second element of the LED package construction largely affects the luminance and the high-luminance light-emitting. Referring to a conventional package illustrated in FIGS. 1A through 1C, a lamp type LED and a surface mounted type LED will be described, separately.
For a lamp type LED package 10 illustrated in FIG. 1A, a metal electrode face of a cup shape with a predetermined angle is provided on the upper side of a lead frame 3B among two lead frames 3A, 3B. An LED device 5 is mounted on the upper side of the metal electrode face. Also, the lamp type LED 10 is packaged by a domed case 7 which is made of transparent molding resin.
On the other hand, as illustrated in FIG. 1B, a surface mounted type LED package 20 has a package 11 which is made of molding epoxy resin. Also, an LED device 15 is arranged on a mounting region where an inclined angle is small, and an electrode (not shown) is connected by a wire 13.
By such package construction, in the lamp type LED package 10, the domed case 7 working as a lens, can control the luminance. Especially, by making the distribution of the luminance angle narrow, the luminance at a predetermined luminance angle can be raised. Also, light which is emitted from a source is reflected on the metal electrode face of the cup shape to raise the luminance. When comparing with the lamp type LED package 10, in the surface mounted type LED package 20, distribution of the luminance angle is made wide by the package 11, and the luminance itself is low. In this manner, the luminance and the distribution of the luminance are largely affected by the package construction. Therefore, in the case of the surface mounted type LED package 20 using molding resin, a development to add a reflecting member is being processed. The reflecting member is a metalized construction having a predetermined reflecting angle and formed at one side of the mounting region.
However, since the construction of the LED package using the molding resin does not have high enough thermal resistance for heat generated by high luminance light, the LED package is not appropriate for the high-luminance emitting-light.
FIG. 1C is a sectional view illustrating a ceramic LED package which is made of a conventional ceramic substrate.
Referring to FIG. 1C, a construction 30 of the ceramic LED package has two ceramic substrates 21 and 22. Each the ceramic substrate has a plurality of ceramic sheets which are laminated. Mounting region for an LED device 25 is located on a lower ceramic substrate 21. An electrode 23 which is connected to the LED device 25 by a wire 27 is extended, through both sides of the ceramic substrates, from the mounting region to the bottom of the substrate. An upper ceramic substrate 22 having a predetermined cavity surrounds the mounting region for the LED device 25.
Here, since the cavity for the mounting region receiving the LED device 25 is formed by punching or cutting, a cutting face is vertically formed at all times as illustrated in FIG. 1C. Therefore, it is difficult to form a reflecting face which can control the luminance angle by making a predetermined inclined plane inside of the cavity. In addition, it makes a manufacturing process complicated and increases the cost that the ceramic substrate 22 supplying the cavity is made of the plurality of substrates which are laminated.
Also, since the heat which is generated by the high luminance light is emitted through only the electrode 23, emitting heat is not rapid, which has a bad influence on characteristics of operation of the LED device 25. Therefore, an LED package which can efficiently emit heat in a ceramic package has been strongly required.
In addition, it takes manufacturing time longer and increase the cost, because the ceramic substrate 22 is made of the plurality of substrates which are laminated.